The present invention relates to an image forming apparatus forming an image on an output medium, and to an image outputting method.
In an image forming apparatus which can output a color image by overlapping monochrome images by using an intermediate transfer medium, an effective image holding length which can hold images corresponding to the largest output medium which can be outputted is given to the intermediate transfer medium. Namely, when the intermediate transfer medium is cylindrical, the circumference thereof is defined to be able to hold the aforementioned largest image, and when the intermediate transfer medium is belt-shaped, the overall length thereof is defined to be able to hold the aforementioned largest image.
Therefore, in an image forming apparatus in which an intermediate transfer medium, to which a length corresponding to the long side of an A3 sized paper is given as the effective image holding length of the intermediate transfer medium, is built in, due to an A4 sized paper being conveyed such that the direction perpendicular to the direction of conveying the paper is the long side direction of the (A4) paper (hereinafter, simply called A4 portrait), a method for simultaneously outputting images of two A4 portrait on the intermediate medium has been put into practice.
Incidentally, when images of two A4 portrait are simultaneously outputted on the intermediate transfer medium, there is the problem that the images cannot be outputted until the image data for two A4 portrait (for two pages) of all of the monochrome images which can be overlapped on the intermediate transfer medium is obtained.
Namely, the compiling time required for compiling image data into output-image data varies, according to the complexity of the data, such as the density and size of the image data per page. Therefore, in an image outputting method in which toner images corresponding to output-image data are sequentially transferred onto an intermediate transfer medium, because the image forming operation starts at the point in time when the total output-image data of the monochrome images which can be overlapped on the intermediate transfer medium has been obtained, there is the problem that the number of image formations (number of outputs) per unit time is small.
An object of the present invention is to provide an image forming apparatus and an image outputting method which can improve the number of image outputs per unit time in an image forming apparatus overlapping images by using an intermediate transfer medium.
According to a first aspect of the present invention, there is provided an image forming apparatus comprising:
an output-image data holding section which holds image data for image output used for forming a toner image;
an image forming section which can hold an electrostatic image that is the basis of the toner image corresponding to the image data;
an electrostatic image developing section which supplies toner to the electrostatic image formed at the image forming section so as to make the electrostatic image visible, and which forms a toner image;
a toner image holding section which holds the toner image formed at the electrostatic image developing section, the toner image holding section being capable of holding two or more toner images in a superposed state, having an effective image holding region of a predetermined size, and being capable of holding toner images for different transfer media in the effective image holding region;
a transfer outputting section which transfers onto a transfer medium the toner image which the toner image holding section holds;
a transfer control section which supplies the transfer medium at a transfer position at which the toner image can be transferred onto the transfer medium between the toner image holding section and the transferring outputting section, when it is informed from a page managing section that at least one toner image, for the transfer medium, which the toner image holding section holds, can be transferred onto the transfer medium; and
a page managing section which senses that the total image data for one transfer medium is inputted, and informs the transfer control section that the output for the transfer medium which the toner image holding section holds can be transferred onto the transfer medium, when the image data corresponding to the toner image for the different transfer medium and the image data for the same transfer medium is inputted in a predetermined order.
According to another aspect of the present invention, there is provided an image forming method comprising:
being able to hold a toner image corresponding to output picture image data of two pages in a range of an effective image holding length when it is sensed that inputted image data is less than xc2xd of the effective image holding length of the intermediate transfer medium, and being able to set a xe2x80x9cdividing outputting modexe2x80x9d which transfers toner images in units of one page onto an output medium at a point in time when output-image data of one page is stored in an image memory;
after compiling image data inputted to an output-image data holding section into output-image data, storing the output-image data in the output-image data holding section;
holding, in a storing section, the amount of the output-image data supplied to the output-image data holding section and page information of individual image data such that pages and colors of toner images correspond, by setting the xe2x80x9cdual outputting modexe2x80x9d;
preparing a transfer medium so as to be able to convey the transfer medium to a transfer position on the basis of the held page information at a predetermined timing after first image data is inputted into the output-image data holding section; and
transferring onto the transfer medium an output image of a page on which a predetermined number of toner images have already been superposed, at a point in time when it is sensed that a predetermined amount of output-image data per one page which enables transfer of an image to be outputted onto the transfer medium has been stored in the output-image data holding section, on the basis of the page information held in the storing section.
According to still another aspect of the present invention, there is provided an image forming apparatus which overlaps toner images of a predetermined number of colors by using an intermediate transfer medium, and which obtains a color image output by collectively transferring the toner images onto a transfer medium, comprising:
an image forming section which can hold an electrostatic image that is the basis of the toner image corresponding to the image data;
an electrostatic image developing section which supplies toner to the electrostatic image formed at the image forming section so as to make the electrostatic image visible, and which forms a toner image;
a toner image holding section which holds the toner image formed at the electrostatic image developing section, the toner image holding section being capable of holding two or more toner images in a superposed state, having an effective image holding region of a predetermined size, and being capable of holding toner images for different transfer media in the effective image holding region;
a transfer outputting section which transfers onto a transfer medium the toner image which the toner image holding section holds;
a transfer control section which supplies the transfer medium at a transfer position at which the toner image can be transferred onto the transfer medium between the toner image holding section and the transferring outputting section, when it is informed from the page managing section that at least one toner image, for the transfer medium, which the toner image holding section holds, can be transferred onto the transfer medium; and
a page managing section which senses that all of the toner images corresponding to the image data for the same transfer medium are stored in the toner image holding section, and transfers onto the transfer medium output for the transfer medium which the toner image holding section holds, regardless of the colors of the toner images held by the toner image holding section.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.